Crontab Formatting
The Cron time string is five values separated by spaces:
* * * * *
- - - - -
| | | | |
| | | | +----- day(week) 0 to 7 (0 and 7 both represent Sunday), or * (no specific value)
| | | +--------- month 1 to 12, or * (no specific value)
| | +------------- day(month) 1 to 31, or * (no specific value)
| +----------------- hour 0 to 23, or * for any value. All times UTC
+--------------------- minute 0 to 59, or * (no specific value)
The Cron time string must contain entries for each character attribute. If you want to set a value using only minutes, you must have asterisk characters for the other four attributes that you're not configuring (hour, day of the month, month, and day of the week).
Common Crontab Expressions
Every Minute
* * * * *
Every Fifteen Minutes
*/15 * * * *
Every Hour
0 * * * *
Every Half Hour
*/30 * * * *
Every Day
0 0 * * *
Weekly
0 0 * * 0
Monthly
0 0 1 * *